Fire extinguishers can be classified according to their total mass, that is to say the weight of the extinguishing agent inside the fire extinguisher. Portable fire extinguishers weigh up to 20 Kg, and they are designed to be easily used by an only user. Heavier fire extinguishers need wheels to be transported and they are called wheeled fire extinguishers.
While a portable fire extinguisher is used by an only person during the initial phase of the fire, the wheeled fire extinguisher is used by two persons to extinguish a fully developed fire: the first user carries and activates the fire extinguisher, the second grabs the horn and directs the flow. If we only have portable fire extinguishers available, it is better to act quickly as soon as we notice the onset of fire; when the fire is already developed, it is necessary to call the firemen.
The duration of operation for wheeled fire extinguishers is longer than for portable ones; this means a higher power during the emission of the extinguishing agent. The flow rate for these fire extinguishers goes from 0.900 Kg/s (for the 18 Kg carbon dioxide fire extinguisher) to 2.200 Kg/s (for the 100 Kg dry chemical fire extinguisher). This because wheeled fire extinguishers put out bigger fires than portable fire extinguishers can manage.
- 50 l foam fire extinguishers.
The actual load must be like the rated load with a 2% factor of safety for wheeled dry chemical fire extinguishers, 5% in other cases. Carbon dioxide fire extinguisher range must be 2 m, dry chemical fire extinguisher range must be 8 m, while all other wheeled fire extinguisher range must be 6 m.
Even duration of operation, that is the time during which the extinguishing agent is emitted without interruption, with the valve being totally open and not keeping in consideration the emission of residual auxiliary gas, must be a standard value, as follows:
|Extinguishing agent||Rated load|
|Foam||50 L||From 35 to 50|
From 30 to 40
From 35 to 45
From 45 to 60
From 20 to 25
From 20 to 30